1. Filed of the Invention
The present invention generally relates to a seatbelt device for securing a passenger to a seat with a seatbelt and ensuring the safety of such passenger upon a vehicle collision, and particularly relates to a seatbelt device comprising a plurality of tension-increasing devices for retracting the seatbelt.
2. Description of the Related Art
A passenger security/protection device for vehicles comprising a retractor for winding and unwinding the seatbelt has been conventionally known. For example, the seatbelt device (passenger security/protection system) for vehicles described in Patent Laid-Open Publication No. Hei 9(1997)-132113 controls the seatbelt retractor upon considering the condition between one""s car and object and/or the condition of one""s car. Particularly, this seatbelt device predicts the collision of one""s car with a distance sensor and increases the seatbelt tension when a collision is unavoidable.
The aforementioned seatbelt device for vehicles is capable of trustworthy prediction in an open road as it predicts the collision of one""s car with a distance sensor. Nevertheless, an accurate prediction is not possible when the visibility of the road is poor, and there is fear of the seatbelt device making a wrong judgment that a collision will not occur, when in fact it will.
In such case, as the seatbelt device does not attempt to increase the seatbelt tension even upon collision, the seatbelt is not wound at such time, and the passenger is not safely secured in a sufficient manner.
The present invention was devised in view of the aforementioned problems, and an object thereof is to provide a seatbelt device capable of reliably securing and protecting a passenger.
Another object of the present invention is to provide a seatbelt comprising a plurality of driving element for providing tension to the seatbelt.
Still another object of the present invention is to structure, compactly, a seatbelt comprising an electromotive retractor and pretensioner for providing tension to the seatbelt.
A further object of the present invention is to generate, with certainty, a desired seatbelt tension for ensuring the safety of the passenger upon collision even if the stroke setting of the pretensioner piston is relatively low.
A still further object of the present invention is to prevent malfunctions and undesired operations of the pretensioner, which is only operable once, while seeking the safety upon a collision.
The present invention for achieving the aforementioned objects comprises: a seatbelt for securing a passenger to a seat; a retractor for retracting one end of the seatbelt; a tongue plate to which the seatbelt passes through; a buckle arranged in the vicinity of the abdominal region of the passenger and connected removably to the tongue plate; a collision prediction device for predicting a collision with an obstacle and generating a collision unavoidable signal when it judges that a collision is unavoidable based on the time or distance to the collision; a collision detection device for generating a collision signal by judging a collision based on the impact acceleration inflicted upon the vehicle upon collision; a first seatbelt tension increasing element for increasing the tension of the seatbelt with the collision unavoidable signal; and a second seatbelt tension increasing element for increasing the tension of the seatbelt with the collision signal.
With the structure above, when the collision prediction device judges that the collision of one""s vehicle is unavoidable, the seatbelt tension is increased before the collision and the passenger is secured to his/her seat as the slack in the seatbelt is reduced. Moreover, when the collision detection device detects the collision of one""s vehicle, the seatbelt tension is further increased immediately after the collision in order to reduce the slack in the seatbelt still more, and the passenger is reliably secured to the seat and the safety of such passenger is ensured thereby.
Preferably, the first seatbelt tension increasing element increases the tension of the seatbelt with the drive of a motor, and the second seatbelt tension increasing element increases the tension of the seatbelt with expansion gas (e.g., combustion gas of powder).
Preferably, the first seatbelt tension increasing element, after activation, continues the operation until a prescribed time (e.g., at least 5 seconds) corresponding to the time or distance to the collision elapses or until the buckle is disengaged. Thereby, the passenger is secured to the seat until the impact of the vehicle collision abates, and such passenger""s safety is ensured. In addition, this prevents the release of the tightened seatbelt due to a misjudgment that the danger of collision has been avoided caused by an error in the distance measurement of the collision prediction device at a close range (For example, it is difficult to measure the distance at close range with an infrared laser radar, and there is a possibility that such distance before collision will be immeasurable.) Preferably, the collision prediction device outputs the collision unavoidable signal at least 0.1 second before the collision, and the first seatbelt tension increasing element operates before the collision.
Preferably, the first and second seatbelt tension increasing element are provided to a center pillar (pillar between the front door and rear door) of the vehicle body or to the retractor installed within the seat.
Preferably, the first seatbelt tension increasing element is provided to the retractor, and the second seatbelt tension increasing element is mounted, for example, on the buckle, lap-outer portion at the lower part of the center pillar of the vehicle body, or the body panel.
Preferably, the collision prediction device predicts the collision by measuring the distance to the obstacle using an infrared laser radar, millimeter wave radar, ultrasonic radar, or stereo camera mounted on the vehicle, and obtains the time until collision by dividing such distance with the speed of one""s vehicle, and judges whether or not the collision is avoidable.
Preferably, the activation of the second seatbelt tension increasing element is judged based on the impact upon the vehicle collision and the activation of the first seatbelt tension increasing element is judged based on the distance between one""s vehicle and the obstacles in its periphery.
With the structure above, as the second seatbelt tension increasing element (gas-expansion or powder pretensioner) operates when there is little slack in the seatbelt due to the operation of the first seatbelt tension increasing element, it is possible to ensure the necessary security of the passenger even if the seatbelt retractability of the second seatbelt tension increasing element is small. Therefore, a gas-expansion (or powder) pretensioner with small seatbelt retractability may be miniaturized and easily housed in a small setup space within a car.
Moreover, by foremost operating the first seatbelt tension increasing element (e.g., electromotive retractor) by predicting the danger of collision and thereafter operating the second seatbelt tension increasing element (e.g., gas-expansion or powder pretensioner) in correspondence with the actual impact of the collision, it is possible to skillfully use in combination a first seatbelt tension increasing element, wherein the seatbelt tension and security are relatively small but may be used repeatedly, and the second seatbelt tension increasing element, wherein the seatbelt tension and security are large but may be used only once.
The seatbelt device according to the present invention comprises: a seatbelt for securing a passenger to a seat of a vehicle; a pretensioner (second seatbelt tension increasing element) for rapidly retracting the seatbelt; an electromotive retractor (first seatbelt tension increasing element) for retracting the seatbelt with a motor; collision detection element for detecting the impact (or collision) of the vehicle; collision prediction element for predicting the collision (or danger thereof) of the vehicle; and a control unit for controlling the operation of, at the least, the electromotive retractor and the pretensioner based on the respective outputs of the collision detection element and the collision prediction element.
The control unit operates the retractor based on the output of the collision prediction element and thereafter operates the pretensioner based on the output of the collision detection element.
Preferably, the control unit changes the detection standard of the collision detection element in accordance with the action/non-action of the retractor.
Preferably, the control unit changes the operation standard of the pretensioner based on the output of the collision detection element when it operates the retractor based on the output of the collision prediction element.
With the structure above, as the pretensioner operates when there is little slack in the seatbelt due to the electromotive retractor, the effect of the pretensioner is large. Moreover, the necessary security of the passenger is ensured even if the seatbelt retractability of the pretensioner is small. The pretensioner can thereby be miniaturized and may be housed in a small setup space within the car As the passenger is secured by the seatbelt being retracted in advance with the retractor, the pretensioner maybe set to operate when the impact upon the collision is substantially large. Therefore, it is possible to prevent malfunctions of the pretensioner and reduce the repair costs upon operation thereof, as the pretensioner may be used only once.